If the developer wishes preliminary approval of the final plat prior to the preparation of such plat, the developer may submit a preliminary plat to the Commission for approval. Such preliminary plat need only contain the information required under Section 200.17 of this chapter. A final plat which conforms substantially to the preliminary plat shall be approved by the Commission within 30 days after application for approval of such final plat, if such plat is submitted within 24 months from the date of approval of the preliminary plat. The final plat shall be approved by the Council within 20 days of the date of its approval by the Commission.